This invention relates to a lid for a fluid pump assembly, and more particularly, to a threaded lid having a gripping formation by which the lid may be turned relative to the pump housing for easy removal and replacement.
The housings of swimming pool pump assemblies customarily include a portion defining a casing for a coarse strainer basket. The strainer basket is designed to remove foreign objects such as sticks, leaves, hair, etc., from the circulating pool water to protect the impeller of the pump and to prevent such objects from reaching a filter through which the pool water is passed for removal of impurities. The strainer basket casing contains a threaded opening to allow the strainer basket to be removed and emptied upon removal and replacement of the lid.
However, problems arise with respect to the removal of the lid prior to the emptying of the strainer basket. For example, although the removal and emptying of the strainer basket is a manual procedure which ordinarily can be performed easily by an individual swimming pool owner, the lids on the strainer basket casings often become fixed in place or stuck, thus inviting the use of a tool such as a large pair of pliers or a hammer to loosen the lid. The use of such tools has a tendency to crack or break the gripping formation, as well as other parts of the lid.
The resistance to unthreading rotation of such lids is due to a number of factors. Individual swimming pool owners tend to over-tighten the lid when replacing it, usually by using the aforementioned tool. Furthermore, small particles such as sand and fragments of leaves and other vegetation become lodged in the mating surfaces of the threads of the lid and the strainer basket casing opening as the water carrying the particles flows through the strainer basket casing. In addition, variations in temperature result in expansion and contraction of the lid relative to the opening of the strainer basket casing, thereby causing the threads to bind. Moreover, some materials of which the lid may be formed, such as plastics, are subject to swelling and deterioration upon exposure to chemicals, such as chlorine, present in the recirculated pool water.